<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>state</title>
</head>
<div id="app"></div>

<body>
    <script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script>
    <script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
    <script src="https://cdn.bootcdn.net/ajax/libs/babel-core/6.1.9/browser.js"></script>
    <script type="text/babel">
        class HelloMessage extends React.Component {
            render() {
                return (
                <div>
                    Hello 
                </div>
                );
            }
        }

        ReactDOM.render(
  <h1>Hello, world!</h1>,
  document.getElementById('root')
);
    </script>
</body>

</html>